Flue construction with separate epoxy liner



July 9, 1968 us ETAL 3,391,506

FLUE CONSTRUCTION WITH SEPARATE EPOXY LINER Filed March 5, 1966 FIG.

FIG. 3

INVENTORS.

RUDOLF GUSNER HARTMUT SCHNEIDER wan- 561%,

ATTORNEYS United States atent O FLUE CONSTRUCTION WITH SEPARATE EPOXYLINER Rudolf Gusner, Erbach, Germany, and Hartmu Schneider, Ulm(Danube), Germany Filed Mar. 3, 1966, Ser. No. 531,492

Claims priority, applicationzGgrmany, Apr. 2, 1965,

4 Claims. cl. 52-309 ABSTRACT OF THE DISCLGSURE Summary of the inventionThis invention generally relates to flues and is particularly directedto a novel flue construction having a heat and corrosion resistant lineror inset.

The term flue is used herein an a broad sense and is deemed to includeany conduit means such as, for example, chimneys, stacks and wastegas-and exhaust pipes for leading away wasteand off gases.

In conventional flue constructions, a variety of different materials areused for lining the interior flue passage through which the gases areconducted. These linings are sometimes in the form of separate liners ortubular insets which are secured or attached to the inner face of theexterior flue wall and which define the actual flue passage throughwhich the gases pass.

During more recent times and in view of the widespread heating by oil ascontrasted to coal and wood, high brick chimneys or flues have beenreplaced by shorter constructions which essentially consist of a pipesurrounded by brick or concrete. A variety of materials have beenproposed for these pipes or insets such as fireproof clays or metal,predominantly in the form of thin steel sheets. Such prior art pipeinsets (hereinafter referred to as liners), when made of fire brick orclay and the like refractory materials are quite suited for carrying oifwaste gases since the material is corrosion and heat resistant. However,such liners have the disadvantage that, due to the brittleness of therefractory material, they are extremely susceptible to shocks andimpact. Such flue constructions therefore have the tendency to crack anddevelop fissures after sometime which, in turn, requires frequentrepair. Moreover, these prior art refractory materials are very heavyand from a ractical point of view, it is not possible to work suchmaterial into thin-walled liners of appreciable lengths. For thisreason, the refractory liners have to be produced in very short lengths.This, in turn, results in the drawback that a flue construction ofordinary height requires a large.

number of liner sections which have to be connected to each other bymortar. This is not only disadvantageous from a technical and assemblyview of view, but the con- 3,3915% Patented July 9, 1968 meeting areasof mortar present weak zones which are easily corroded and subject toattack, particularly by chemically aggressive combustion gases.Moreover, the many mortar areas have a tendency of being negativelyaffected 'by atmospheric influences to which the flue construction isexposed. Liners made of refractory bricks and clay have the additionaldisadvantage that, due to their brittleness and weight, it is difficultto ship and handle them at the building site. Still a furtherdisadvantage of liners of the conventional construction is that theypresent a rough interior surface which offers considera'ble frictionalresistance to the waste gas flow. This, in turn, results in deposits andpockets of pre-ciptiated solid material along the flue wall which affectthe effectiveness of the flue.

In respect to pipe insets or liners made of metal, such as sheet steel,experience has demonstrated that this material is not particularlysuitable for conveying hot and chemically aggressive waste gases.Self-supporting steel fines without surrounding brick have the drawbackthat their exterior surface is constantly exposed to the atmospherewhich has a strong corrosive effect, particularly with fluctuatingtemperature conditions, to wit, when the fiue is alternately heated andcooled. The interior surface of such flues is particularly stronglyattacked when the waste gases are below a predetermined temperature inwhich event acid-containing deposits are formed on the wall surface.Moreover, such metal flues are not suitable for fixed assembly sincethey have a tendency strongly to expand upon heating and due to theirheat conductivity, conduct the heat of the off-gases to theirsurroundings. This increases the fire danger and in many localities theuse of metal flues is therefore prohibited by local ordinances.

Accordingly, it is a primary object of the present invention to overcomethe disadvantages of the prior art flue constructions having liners ofmetal or refractory materials such as clay or brick.

It is also an object of this invention to provide a flue constructionhaving a heat and corrosion resistant inset or liner of a plasticmaterial, which is superior to prior art constructions and may beproduced in a simple and inexpensive manner.

Generally, it is an object of this invention to improve on the art offlue constructions as presently practiced.

Briefly, and in accordance with this invention, the flue constructionhas an exterior confining wall and an interior liner of a heat andcorrosion resistant synthetic resin admixed with fillers. It has beenascertained that liners of viscous synthetic resins of the glycidylether of phenol formaldehyde type, admixed with fillers such as quartz,asbestos, glass fibers or dolomite powder yield superior results.

It will be appreciated that, prior to this invention, a seriousprejudice existed against the use of plastic materials in flueconstructions, since it was generally assumed that plastics are not ableto withstand the temperatures and chemical conditions to which flues aregenerally subjected by the combustion or waste gas flow. Surprisingly,it has now been found that this prejudice is unfounded if a liner of theindicated kind is employed. Experiments have demonstrated that theinventive flue construction fitted with an inventive liner of a glycidylether of phenol formaldehyde-filler material is superiorly 3 suitablefor conducting any kind of waste gas, including strongly aggressivecombustion gases at very high temperatures. The inventive constructionis thus suitable for use .in chimneys and flues in apartment buildingsand in industrial plants.

The inventive liners of synthetic resin and fillers are preferablyproduced in the form of jointless pipes by ieans of centrifugal castingprocedures. The individual pipes may be of considerable length,dependent on the size of the casting equipment. If several lengths ofpipe are necessary for a single flue construction, the individualsections may be easily connected together by chemical or mechanicalmeans.

The fillers should be used in comminuted form and homogeneously anduniformly distributed through the synthetic material. The fillersconsolidate and reinforce the liner structure and increase the flashpoint of the resin. Moreover, the presence of the fillers advantageouslyalters the heat conductivity of the material. It is also within thescope of this invention to add chemicals to the liner mixture whichreduce the inflammability of the pipes or which have a tendency toextinguish fire. Further, antistatica may be added in order to minimizethe undesired effect of strong electrostatic charges of the plasticmaterial.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated and described a preferredembodiment of the invention.

In the drawings:

FIG. 1 is a sectional view through one embodiment of an inventive flueconstructions;

FIG. 2 is a detail view corresponding to FIG. 1; and

FIG. 3 is a plan view of FIG. 1.

Referring now to the figures, it will be noted that FIG. 1 illustrates aflue construction generally indicated by reference numeral 100. The flueis located above a fire, diagrammatically indicated by reference numeral2 and extends in an upright position above its supporting wall or roofmember 4. The flue proper consists of an outer confining wall, generallyindicated by reference numeral and an interior liner indicated byreference numeral 15. The exterior confining wall 19 consists ofindividual bricks 11 of conventional refractory material which arejoined together as indicated by reference numeral 12. Since the exteriorbrick wall construction of the flue 100 is of conventional design nofurther description in this respect would appear to be necessary.

In accordance with the invention, the liner 15 consists of a syntheticresin admixed with filler material. The composition of the liner mixtureis indicated in detail in the following example. It will be noted thatthe interior liner 15 consists of individual sections 16 which arejoined together in any suitable manner as, for example, by cementing.For this purpose, the individual pipe sections 16 have upwardlyprojecting flange portions 17 which fit into complementarily shapedrecess portions 18 of the adjoining pipe sections. It should also beappreciated that the liner 15 composed of the pipe section 16 does notactually contact the brick wall It) but that there is a space 19 betweenthe pipe 15 and the brick wall 10 to permit for expansion. In order tomount the pipe 15 within the brick wall 10, spacer means 21 of suitableconstruction may be provided.

The invention will now be described in connection with the followingexample, it being understood, however, that this example is given by wayof illustration and not by way of limitation, and that many changes inchoice of starting compounds and process conditions in general may beeffected without departing in any way from the scope and spirit of thisinvention as recited in the appended claims.

by centrifugally casting a mixture consisting of 50 parts by weight ofan epoxy novolac resin of the formula our -c in U ll wherein the averagevalue of n is about 1.5, the resin being admixed with about 1% ofantimonytrioxidc to decrease the inflammability of the material;

50 Parts by weight of quartz powder of an average particle diameter of 1to 5 micron;

Parts by weight of a curing agent, such as for eX- anrple p,p'-methylenedianiline and 2 Parts by weight of a hardening catalyst ofconven tional composition.

It will be appreciated that other resins of the glycidyl ether of phenolformaldehyde type may be used for the manufacture of the inventiveliners.

The filler content of the pipes may be varied between 35 to 70% byweight depending on the size of the particles of the filler. It has beenestablished that the heat conductivity of the material is increased, thesmaller the size of the filler particles. For this reason, extremelysmall particles are preferred. Particulate filler material of a particlesize of 0.5 to microns is particularly suitable.

The mixture of this example was cast in a centrifugal casting machine toform a jointless pipe section having an inner diameter of millimetersand a wall thickness of 6 millimeters.

Tests were performed with the inventive liners. The pipe sections werethus used as liners in a brick chimney of the nature shown in thefigures. It was found that the inventive pipe liners are completely heatresistant in respect to waste gases having a temperature of 620 C. andabove. The heat resistance remained for a long period of time. Testswere also performed in which combustion gases emanating fromintentionally incompletely burnt heating oil were passed through theliner for eight hours. These combustion gases thus contained a largeamount of soot. It was ascertained that no significant soot depositionor precipitation occurred which is contrary to the experience had inconnection with the conventional brick or clay lined lines.

The inventive pipe liners, besides their surprisingly high heatresistance have thus the additional advantage that no deposits areformed within the flue passage which could lead to chimney fires.Therefore, flue or chimney constructions with the inventive liners havea considerable ad vantage over conventional constructions. The inventionconstruction has a long life and requires insignificant main tenanceonly. Due to the smooth inner face of the liners, friction of laminarwaste gas flow is reduced to a minimum and undesired turbulences of thewaste gas flow caused by friction is thus prevented.

An additional advantage of the plastic liners is that they are easilytransported and assembled in view of their light weight and haveconsiderable tensile strength. The danger of breakage is non-existent.The connection of the individual sections to each other may be effectedby screwing, cementing or welding. In this manner, the assembly ofchimney constructions is considerably facilitated and accelerated.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In a flue construction having an outer confining wall and an interiorliner, the improvement comprising that the interior liner consist of aliner pipe separate from said outer confining wall formed of a syntheticresin of the glycidal ether of phenol formaldehyde type admixed with afiller material for increasing the heat conductivity of the liner pipe.

2. In a flue construction as set forth in claim 1 wherein said fillermaterial consist of quartz, glass, asbestos or dolomite powder having aparticle size of between about 0.05 to 100 microns.

3. In a flue construction as set forth in claim 1 wherein said linerpipe is formed by centrifugal casting.

4. In a flue construction having an exterior confining wall and aninterior liner for the passage therethrough of flue gases, theimprovement which comprises that the liner is a separate jointless pipeessentially consisting of 35 to 70% of filler particles of a size of0.05 to 100 microns and about 30 to 65% of an epoxy novolac resin of theformula References Cited UNITED STATES PATENTS 3,094,498 6/ 1963Landolt.

3,177,902 4/ 1965 Rubenstein.

3,288,171 11/1966 Hucks 138145 3,297,056 1/ 1967 McLauglin.

OTHER REFERENCES D.E.N. Epoxy Novolac Resins Form No. l-143A by PlasticsDept., Dow Chemical Co., Midland, Mich. pp. 1, 4 and 15. Copy receivedNov. 17, 1965, copy group 145.

JOHN E. MURTAGH, Primary Examiner.

